Refractory period stimulation (RPS) therapy includes therapeutic electrical stimulation that when delivered to myocardial tissue does not trigger or evoke depolarization response from the surrounding myocardial tissue (i.e., does not trigger an electromechanical contraction of the heart). The stimulus does not trigger a mechanical contraction because the stimulus is delivered to the myocardial tissue during a period when the tissue is refractory. Myocardial tissue in an absolute refractory state cannot be captured regardless of the amount of electrical energy delivered thereto while such tissue in a relatively refractory state can be captured provided adequate energy delivery during a given pulse.
The inventor has discovered a particularly efficient enhanced RPS therapy delivery regimen that improves ventricular performance for heart failure patients.